Simple tweaks can make wastewater treatment less polluting

Summary

Podcast Summary: Climate Connections

Episode: Simple tweaks can make wastewater treatment less polluting
Date: July 23, 2026
Host: Dr. Anthony Leiserowitz (Yale Center for Environmental Communication)
Guest: Jose Poro (CEO, Cobalt Water Global)

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Episode Overview

This brief yet informative episode explores how wastewater treatment plants—essential for cleaning sewage—can inadvertently contribute to climate change and ozone depletion via nitrous oxide emissions. Dr. Anthony Leiserowitz discusses with Jose Poro how targeted, simple operational adjustments can dramatically reduce these emissions, offering climate and public health benefits.

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Key Discussion Points and Insights

Wastewater Treatment and Nitrous Oxide Emissions

• Role of Treatment Plants: Remove pollutants from sewage to protect natural waterways ([00:01]).

  • "Wastewater treatment plants remove pollutants from sewage before it returns to lakes, rivers, and oceans." — Dr. Leiserowitz

• Unintended Pollution: Standard processes can inadvertently release nitrous oxide—a significant greenhouse gas ([00:12-00:28]).

  • "But that treatment process can produce some harmful pollution of its own." — Dr. Leiserowitz

• Environmental Impact:

  • Greenhouse gas: Nitrous oxide is "a powerful global warming gas." ([00:24])
  • Ozone impact: "Nitrous oxide is also an ozone depleting gas," as noted by Jose Poro ([00:28]).

Source of Nitrous Oxide

• Nitrogen Removal:
  • Nitrogen from human waste must be removed to avoid nutrient pollution in waterways ([00:31-00:36]).
  • When microbial breakdown of nitrogen is not optimal, nitrous oxide can form as a byproduct.

Simple Solutions Through Process Tweaks

• Operational Adjustments:

  • Aeration (oxygenating water) can be reduced at targeted times to minimize undesired emissions ([00:43]).
  • "The problem can often be fixed through simple tweaks— from, for example, aerating the water less at certain times so less oxygen gets in." — Dr. Leiserowitz

• Tech-Driven Monitoring:

  • Cobalt Water Global applies machine learning to help utilities fine-tune these processes ([00:50]).
  • "So his company uses machine learning to help utilities monitor and fine-tune their processes." — Dr. Leiserowitz

Impact and Effectiveness

• Emission Reductions:

  • Poro reports significant success: "We've been able to achieve up to 80 to 90% reductions in the N2O emissions from making simple process adjustments" ([01:06]).

• Balanced Outcomes:

  • Plants can continue to clean water efficiently without contributing as heavily to atmospheric pollution ([01:14]).
  • "...water treatment plants can clean the water without adding as much pollution to the atmosphere." — Dr. Leiserowitz

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Notable Quotes

• On the dual challenge:
  • "But that treatment process can produce some harmful pollution of its own." — Dr. Leiserowitz [00:12]
• Explaining nitrous oxide:
  • "Nitrous oxide is also an ozone depleting gas." — Jose Poro [00:28]
• On practical solutions:
  • "We've been able to achieve up to 80 to 90% reductions in the N2O emissions from making simple process adjustments." — Jose Poro [01:06]

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Important Timestamps

• 00:01 — Introduction to the issue.
• 00:24 — Nitrous oxide introduction as a greenhouse and ozone-depleting gas.
• 00:43 — Aeration tweaks explained.
• 00:50 — Machine learning for optimization.
• 01:06 — Quantified results: 80-90% emission reduction.

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Conclusion

This episode of "Climate Connections" provides a clear, actionable insight into a hidden source of emissions and demonstrates that climate solutions can sometimes be as simple as making small but strategic process changes. By leveraging technology and operational tweaks, wastewater plants can dramatically cut their climate footprint—offering hope for scalable change.

Transcript

[A]

I'm Dr. Anthony Liesiewicz, and this is Climate Connections. Wastewater treatment plants remove pollutants from sewage before it returns to lakes, rivers, and oceans. But that treatment process can produce some harmful pollution of its own. Jose Poro is CEO of Cobalt Water Global, a company that helps water utilities reduce their nitrous oxide emissions. Nitrous oxide is a powerful global warming gas.

[B]

Nitrous oxide is also an ozone depleting gas,

[A]

and it can be created as an unintended byproduct of wastewater treatment during the removal of nitrogen. Nitrogen is present in people's urine and it has to be removed because if it ends up in waterways, it can cause harmful algae growth and other problems. But under certain conditions, the microbes that break down nitrogen can produce nitrous oxide. Paro says the problem can often be fixed through simple tweaks from, for example, aerating the water less at certain times so less oxygen gets in. So his company uses machine learning to help utilities monitor and fine tune their processes.

[B]

We've been able to achieve up to 80 to 90% reductions in the N2O emissions from making simple process adjustments

[A]

so water treatment plants can clean the water without adding as much pollution to the atmosphere. Climate Connections is produced by the Yale center for Environmental Communication. To learn more about climate change, visit climateconnections. Connections. Org.